ios scheduledTimerWithTimeInterval for amount of time

Question

I want to use scheduledTimerWithTimeInterval to do a periodic task for certain amount of time lets say one hour. but How do I implement on my code. Here is my code:

timer = [NSTimer scheduledTimerWithTimeInterval: 0.1
                                          target: self
                                        selector: @selector(doSomething:)
                                        userInfo: nil
                                         repeats: YES];

Solution

Lets assume for a minute .

Here is simple scenario ,

int remainingCounts;
NSTimer *timer;

timer = [NSTimer scheduledTimerWithTimeInterval:1 target:(self) selector:@selector(countDown) userInfo:nil repeats:YES];
remainingCounts = 60;   // int remainingCounts ;...

Method being called for every sec.

-(void)countDown {
    NSLog(@"%d", remainingCounts);
    // Do Your stuff......
    if (--remainingCounts == 0) {
        //[self dismissViewControllerAnimated:YES completion:nil]; 
        [timer invalidate];
    }
}